NASA held back on the possibility of Crew survival at the time because they did not want to further upset the public.
The information was there but it was not something that was explicitly reported by the media.
All this info and when it was available, depends on where you were living at the time.
Here in central FL. it was reported 3 days later that a high level NASA source confirmed they believed the astronauts survived until impact as there were fragments of transmissions and astronaut telemetry (BP, heart rate, etc.) well after the infamous "uh-oh" transmission.
The fact that 90%+ of the shutttle, both boosters, the bodies of all (what was left) were recovered, that only 4 (incomplete) astronaut remains were identifiable (DNA was not used) and that the remaining unidentifiable remains were entombed with the Challenger's remains at the memorial site was reported, too, but is probably not common knowledge either.
Here in central FL. we knew about the Apollo 1 disaster within minutes of it happening.
It occurred just as the evening local news had ended and the network national news came on 6:30pm EST.
Local news interrupted and carried live the events and it was confirmed all 3 we're dead within an hour.
I well remember the sight of a smoking black pillar suddenly emanating from the gantry on the live TV playback shot, which we later learned was when the capsule hatch was opened.
Video of the capsule interior (after the remains were removed) were shown on local news in following days, that I don't believe went national, because of next of kin objections (but not NASA objections at the time, that came later).
Local stations "leaked" the Apollo 13 problem live after reporting it to the networks, which aired it 30-45 minutes later.
Being a big deal here in FL,
nothing about the space programs goes unnoticed, unfilmed, or uninvestigated and high level inside sources are readily available and the local stations are not bashful about reporting, except for the clandestine military launches.
As I said, depends where you live.
We know nothing here about the infamous snowplow misdirection by New York's new mayor

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BTW - VAB tours have been extended until 2/23, if you want to see inside, hurry as it may be your last chance, since it is being turned over to the next gen "Space Launch System" as an assembly area and will probably not be open to the public again.